Compressor suction line by-pass means



Jan. 30, 1968 W. .1. BARBIER 3,365,905

I COMPRESSOR SUCTION LINE BY-PASS MEANS Filed March 7, 1966 United States Patent O 3,365,905 COMPRESSR SUCTION LNE BY-PASS MEANS William J. Barbier, St. Louis County, Mo., assignor to .Faches-Evans Manufacturing Company, St. Louis, Mo., a corporation of Missouri Filed Mar. 7, 1966, Ser. No. 532,193 2 Claims. (Cl. 62-196) The present invention relates generally to compressor operated systems and more particularly to compressor operated refrigeration systems and the like.

It is common practice to use compressors to circulate gases and fluids in refrigeration and other types of systems. In most known systems of this type, system control is maintained by periodically energizing and deenergizing the compressor or by controlling or restricting system flow in response to a temperature or other condition being produced. For the sake of economy, maintenance and operating eiiiciency it is usually desirable to maintain the compressor in a continuously operating condition even when the system is idling or in its off cycle, and yet allow some flow of lubricant to and through the compressor to prevent starving the compressor and to prevent the production of undesirable system pressures. Recent developments particularly in the valve art have made it possible to relatively accurately control the liow of refrigerant or other substances in a system in order to accurately control the condition or temperature being produced. However, these developments have not taken into account compressor starvation and overheating of the compressor motor means nor have they overcome the problems associated with the production of undesirable excessively low compressor crankcase pressures caused by lack of circulating lubricant in the system. The subject invention overcomes these and other disadvantages and shortcomings of the known systems by providing bypass means preferably in association with the suction line of a compressor to allow some fluid or lubricant to return to the compressor for circulation even though the system is in an olf cycle. The subject by-pass means may optionally also include unidirectional relief valve means to prevent flow of fluid in the system during on cycles.

A principal object of the present invention is to improve the operating characteristics and efficiency of compressors and systems employing compressors.

Another object is to provide means to circulate lubricant through a compressor employed in a refrigeration or other system under all operating conditions of the systern.

Another object is to reduce maintenance, prevent the production of excessively low compressor pressures and prolong the life of compressors.

Another object is to prevent starving compressors and like devices under various operating and load conditions.

Another object is to improve the operating characteristics of refrigeration and air conditioning systems.

These and other objects and advantages of the present invention will become apparent after considering the following detailed speciiication which covers a preferred embodiment in conjunction with the accompanying drawing, wherein:

FIG. 1 is a schematic diagram of a refrigeration system incorporating the improvements of the present invention;

FIG. 2 is a fragmentary schematic diagram showing a modified form of the subject improvements; and

FIG. 3 is an enlarged fragmentary cross-sectional view taken on line 3-3 of FIG. 2.

Referring to the drawing by reference numbers, number indicates a compressor having its high pressure outlet connected to a conduit 12 and its low pressure suction side connected to another conduit 14. The opposite end of the high pressure conduit 12 is connected to the inlet side of a condenser 16, and the outlet of the Condenser 16 is connected by conduit 18 to the inlet of a receiver 20. The outlet of the receiver Ztl is connected by another conduit 22 to one side of an expansion device or valve 24 which has its opposite side connected by conduit 26 to the inlet of an evaporator 28. The evaporator 28 has a main outlet connection connected by conduit 30 to one side of a throttling control valve 32. The evaporator 28 also has a secondary outlet connection which is connected to one end of a by-pass line 34. The by-pass line 34 has much less iiow capacity than the conduit 30 and the valve 32, when open, and is connected to the outlet side of the evaporator 28 near the bottom where lubricant accumulates when the system is operating. The opposite end of the bypass line 34 is connected to the compressor suction line 14 downstream from the throttling valve 32. This is done to provide a limited ow connection around the valve 32 in order to allow some lubricant to iiow back to the compressor even when the valve 32 is closed. The throttling valve 32 may be of a construction such as disclosed in copending U.S. Miller application Ser. No. 305,522, iiled Aug. 29, 1963, now Patent No. 3,242,688.

The throttling valve 32 has a control connection to a temperature responsive element 36 positioned to respond to a predetermined environmental condition being controlled such as a temperature condition produced by the evaporator 28. When the temperature sensed by the element 36 is relatively high the throttling valve 32 will be open to increase How through the system and to increase refrigeration. Most of this flow will pass through the conduit 30 and the valve 32 to producean on cycle. As the temperature drops, a point will be reached where the valve 32 will close due to contraction of pressure in the element 36 thereby throttling flow in the system. Under these conditions the by-pass line 34 will operate to permit some ow of lubricant from the evaporator back to the compressor 10. The lubricant, as already noted, is preferably taken from a low point on the outlet side of the evaporator 28 to assure that it will be mostly lubricant, and will enable the compressor to continuously operate without overheating its motor and/or without producing undesirable system pressures particularly excessively low pressures inside the compressor itself. Without this by-pass feature the compresor, if allowed to continue to run during off cycles, would tend to overheat producing maintenance and other problems and the starving of the compressor would also tend to develop undesirable pressures in the system.

FIG. 2 shows a by-pass conduit which has been modi-- iied to include a unidirectional pressure relief valve 38. The details of the pressure relief valve 38 are shown in FIG. 3 and include a housing 4i) with a chamber 42 therein. The housing 40 is connected into the by-pass line 34 and includes an annular portion 44 which is formed into a valve seat 46. The valve seat 46 is normally closed by engagement with a movable valve member 48 which is biased thereagainst by a spring 5i). The spring 5G has one end engaged with the movable valve member 48 and its opposite end is anchored against a shoulder 52. When the throttling valve 32 is open relatively little pressure difference will exist across the by-pass line 34, and the spring Sil will be able to maintain the relief valve 3S closed to prevent ow therethrough. However, when the 'throttling valve 32 is closed, the compressor suction force developed in the suction line 14 will be sufficient to open the relief valve 38 to allow some of the lubricant trapped at the outlet side of the evaporator 21S to flow to the compressor. The relief valve 38 therefore is included to prevent fiow through the by-pas line during on cycles but permits ow of lubricant during off cycles. The valve 38 may also prevent excessive fiow to the compressor during on cycles caused by high pressure drops across the throttle valve 32, and/ or high pressures across the by-pass line due to the length of suction line in parallel with the by-pass line. Normally, however, the relief valve 38 will only open when the pressure drop thereacross is higher than the pressure drop across the parallel circuit which is when the throttling valve 32 is closed.

The principles of the present invention can also be applied to systems other than refrigeration systems which are operated by compressors and are subject to being controlled by means which throttle the flow. In all such systems, the subject improvements substantially reduce system maintenance, stabilize the load on the compressor and reduce or eliminate undesirable system pressures. They also increase efiiciency and minimize wear and tear on the compressor caused by starting and stopping and by substantial changes in the load on the compressor.

rl`hus there has been shown and described novel means for improving the operating characteristics of compressor operated systems such as refrigeration systems and the like which fulfill all of the objects and advantages sought therefor. Many changes, modifications, variations, and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawing. All such changes, modifications, variations, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.

What is claimed is:

1. A refrigeration system comprising a compressor having a high pressure outlet side and a suction return inlet, said system including a condenser, an expansion device, an evaporator, and a temperature responsive throttling valve serially connected between the compressor outlet and the suction inlet, said temperature responsive valve having a temperature responsive means positioned to respond to a temperature produced by the evaporator, said evaporator having an outlet including reservoir means for accumulating liquid circulating in the system, first conduit means connected between the outlet side of the evaporator and the throttling valve, and a second conduit means of substantially more limited flow capacity than the first conduit means connected to the outlet side of the evaporator in communication with the reservoir means and the compressor section inlet to provide means for fluids that accumulate in the reservoir means to flow back to the compressor when the throttling valve is closed.

2. The system defined in claim 1 wherein said second conduit means include unidirectional valve means and means for biasing said unidirectional valve means closed when the throttling valve is open.

References Cited UNITED STATES PATENTS 2,063,496 12/1936 Evers 62-217 XR 2,282,385 5/1942 ShaWhan 62--217 XR 2,759,674 S/1956 Jorgensen 62--217 XR 2,966,044 l2/l960 Mitchell 62-217 3,084,521 4/1963 Schlotterbeck 62-217 XR MEYER PERLIN, Primary Examiner. 

1. A REFRIGERATION SYSTEM COMPRISING A COMPRESSOR HAVING A HIGH PRESSURE OUTLET SIDE AND A SUCTION RETURN INLET, SAID SYSTEM INCLUDING A CONDENSER, AN EXPANSION DEVICE, AN EVAPORATOR, AND A TEMPERATURE RESPONSIVE THROTTLING VALVE SERIALLY CONNECTED BETWEEN THE COMPRESSOR OUTLET AND THE SUCTION INLET, SAID TEMPERATURE RESPONSIVE VALVE HAVING A TEMPERATURE RESPONSIVE MEANS POSITIONED TO RESPOND TO A TEMPERATURE PRODUCED BY THE EVAPORATOR, SAID EVAPORATOR HAVING AN OUTLET INCLUDING RESERVOIR MEANS FOR ACCUMULATING LIQUID CIRCULATING IN THE SYSTEM, FIRST CONDUIT MEANS CONNECTED BETWEEN THE OUTLET SIDE OF THE EVAPORATOR AND THE THROTTLING VALVE, AND A SECOND CONDUIT MEANS OF SUBSTANTIALLY MORE LIMITED FLOW CAPACITY THAN THE FIRST CONDUIT MEANS CONNECTED TO THE OUTLET SIDE OF THE EVAPORATOR IN COMMUNICATION WITH THE RESERVOIR MEANS AND THE COMPRESSOR SECTION INLET TO PROVIDE MEANS FOR FLUIDS THAT ACCUMULATE IN THE RESERVOIR MEANS TO FLOW BACK TO THE COMPRESSOR WHEN THE THROTTLING VALVE IS CLOSED. 